This invention relates to an arrangement for open end friction spinning machines of the type having two friction rollers that are arranged adjacent to one another to form a wedge-shaped yarn forming gap therebetween and which rollers are driven in the same rotational direction. At least one of the friction rollers has a perforated shell, on the inside of which a suction insert is arranged that is connected to a vacuum pipe, said suction insert exhibiting a suction slot directed to the area of the wedge-shaped gap.
In the case of a known device of the above-mentioned type disclosed in Published European Patent Application (EP-OS) 52 412, a tube shaped suction insert is disposed with its exterior wall so that it is close to the inside surface of the perforated roller shell and is provided with a suction slot which is aimed at the wedge-shaped gap. Another interior insert which has a slot extending diagonally to the suction slot is provided within the suction insert and is arranged so that it can be turned. Through the rotation of the interior insert, the suction slot can be closed progressively in the axial direction. In the case of the known design, this facilitates the return of a thread end into the spinning aggregate for a start spinning process. The relative position of the suction slot with respect to the wedge-shaped gap and the suction effect exercised by it during the normal spinning operation are not adjustable. In order to be able to house and actuate the rotatable interior insert within the suction insert, a very expensive construction is provided which also results in an expensive mounting or bearing for the shell of the roller.
The present invention provides for a simplified construction of an open-end friction spinning machine of the above-mentioned type, where the relative position of the suction slot with respect to the wedge-shaped gap and/or the resultant suction effect can be adjusted precisely and, as necessary, can be changed to adapt to changed spinning conditions. Thus, the preferred embodiments of the invention provide for differential friction effect and adjustment thereof at different axial sections of the fiber feeding zone.
This objective is achieved according to the invention by providing that the suction insert is formed by a pipe that is held fast with respect to rotation and is connected to a vacuum pipe and an intermediate connection piece that essentially fills the space between the shell and the pipe. The intermediate connection piece has a suction slot that is communicated with the inside space of the pipe and is arranged on the pipe so that it can be adjusted in the circumferential direction and/or the axial direction, said pipe serving as the shaft for one or several roller bearings supporting the perforated friction roller shell, which shell is driven directly by a belt drive. In preferred proposed commercial embodiments, the belt drive will drive a plurality of friction roller shells arranged at respective separate spinning units on any spinning machine frame.
The development is constructively very simple, especially for the mounting and the drive of the friction rollers. The arrangement additionally advantageously accommodates a simple manner of adjustment of the relative position of the suction slot with respect to the wedge-shaped slot and/or its suction effect (i.e., the direction and/or magnitude of the suction air flow), if necessary, to adapt to changed spinning conditions.
In the case of an especially simple preferred embodiment, the suction insert is formed by a cylindrical pipe or tube and a pipe-shaped cylindrical intermediate piece is fitted by sliding it onto the pipe. A slot-shaped connection opening to the suction slot of the cylindrical intermediate piece, provided on the pipe. The mounting of the perforated roller shell on the pipe is preferably via roller bearings of the same size as the inside of the shell, which arrangement is advantageous for the stressing and bearing loads and especially for accomodating series production. In this case, it is advantageous if the intermediate piece is made of plastic. This allows especially narrow tolerances to be maintained, with respect to the interior surface of the shell, since a possibly occuring slight touching of the intermediate piece by the shell would not result in any damage.
In a useful development of the invention, it is provided that the cylindrical pipe projects beyond the ends of the shell which, in the area of its two ends, is mounted on the pipe by roller bearings, so that the intermediate piece is arranged between the roller bearings. Thus, the intermediate piece also serves as a seal between the area of the vacuum, namely the suction slot, and the roller bearings. In this case, it is especially advantageous if the pipe-shaped intermediate piece is provided on its exterior surface with annular grooves and/or torri sealing its suction slot with respect to the roller bearing or roller bearings. Thus, at certain points, very narrow sealing gaps can be maintained, while in addition, a type of labyrinth seal is created. For the same purpose, it is also advantageous if the suction slot of the intermediate piece is bounded by at least one groove extending in parallel to its contour. Here, also in the manner of a labyrinth packing the suction effect resulting from the suction slot is limited with respect to area. In order to be able to adjust the intermediate piece, it is advantageous for the shell to be provided with an access recess located in axial direction outside the area of the suction slot of the intermediate piece, the intermediate piece being provided with a working surface for a tool in the area of this access recess.
In another development of the invention, the intermediate piece is provided with at least one recess extending approximately over the perforated area of the shell and being open in the direction of the shell, said recess being spaced from the suction slot. This recess collects particles, such as fiber residues or dust that enter between the shell and the connection so that they do not interfere with the spinning operation. This recess must then be cleaned during a maintenance procedure. In a useful further development, it is provided that the recess of the intermediate piece is connected with the inside of the pipe, via openings. In this case, deposits can be sucked out of the recess of the intermediate piece and can be removed.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments in accordance with the present invention.